Electrical degradation by electrical treeing has many similarities with mechanical cracking of the material. For a system containing microcapsules, one or more of the branches of the electrical tree will likely break a capsule, filling the electrical tree with the liquid monomer. As the tree structure is interconnected, most of the tree structure is likely to be filled. This depends on the partial pressure and viscosity of the monomer and the surface tension of the hollow tubes, but also on the availability of monomer relative to the dimensions of the hollow tubes. The filling itself should extinguish critical discharges, making further growth less likely. Upon polymerization, further development of the electrical tree should halt, or at least be significantly delayed. A series of tests, where high voltage was applied to metal needles cast in epoxy to induce electrical tree growth, was conducted to study electrical degradation and breakdown of the thermoset insulation with and without microcapsules with monomer (healing agent). The experimental setup used provides the possibility of studying the inception and propagation of the phenomena using an optical microscope. This setup was used to study the interaction between the electrical tree and the micro-capsules in situ, and showed the direct attraction of the electrical trees towards the microcapsules.